Start making gendwarfksyms more useful by adding support for expanding DW_TAG_base_type types and basic DWARF attributes.
Example: $ echo loops_per_jiffy | \ scripts/gendwarfksyms/gendwarfksyms \ --debug --dump-dies vmlinux.o ... gendwarfksyms: process_symbol: loops_per_jiffy variable base_type unsigned long byte_size(8) encoding(7) ... Signed-off-by: Sami Tolvanen <samitolva...@google.com> Acked-by: Neal Gompa <n...@gompa.dev> Reviewed-by: Petr Pavlu <petr.pa...@suse.com> --- scripts/gendwarfksyms/dwarf.c | 159 ++++++++++++++++++++++++++++++++++ 1 file changed, 159 insertions(+) diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c index 81df3e2ad3ae..35fd1dfeeadc 100644 --- a/scripts/gendwarfksyms/dwarf.c +++ b/scripts/gendwarfksyms/dwarf.c @@ -3,8 +3,20 @@ * Copyright (C) 2024 Google LLC */ +#include <stdarg.h> #include "gendwarfksyms.h" +#define DEFINE_GET_ATTR(attr, type) \ + static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \ + type *value) \ + { \ + Dwarf_Attribute da; \ + return dwarf_attr(die, id, &da) && \ + !dwarf_form##attr(&da, value); \ + } + +DEFINE_GET_ATTR(udata, Dwarf_Word) + static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value) { Dwarf_Attribute da; @@ -67,6 +79,109 @@ static void process(const char *s) fputs(s, stderr); } +#define MAX_FMT_BUFFER_SIZE 128 + +static void process_fmt(const char *fmt, ...) +{ + char buf[MAX_FMT_BUFFER_SIZE]; + va_list args; + + va_start(args, fmt); + + if (checkp(vsnprintf(buf, sizeof(buf), fmt, args)) >= sizeof(buf)) + error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE"); + + process(buf); + va_end(args); +} + +#define MAX_FQN_SIZE 64 + +/* Get a fully qualified name from DWARF scopes */ +static char *get_fqn(Dwarf_Die *die) +{ + const char *list[MAX_FQN_SIZE]; + Dwarf_Die *scopes = NULL; + bool has_name = false; + char *fqn = NULL; + char *p; + int count = 0; + int len = 0; + int res; + int i; + + res = checkp(dwarf_getscopes_die(die, &scopes)); + if (!res) { + list[count] = get_name_attr(die); + + if (!list[count]) + return NULL; + + len += strlen(list[count]); + count++; + + goto done; + } + + for (i = res - 1; i >= 0 && count < MAX_FQN_SIZE; i--) { + if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit) + continue; + + list[count] = get_name_attr(&scopes[i]); + + if (list[count]) { + has_name = true; + } else { + list[count] = "<anonymous>"; + has_name = false; + } + + len += strlen(list[count]); + count++; + + if (i > 0) { + list[count++] = "::"; + len += 2; + } + } + + free(scopes); + + if (count == MAX_FQN_SIZE) + warn("increase MAX_FQN_SIZE: reached the maximum"); + + /* Consider the DIE unnamed if the last scope doesn't have a name */ + if (!has_name) + return NULL; +done: + fqn = xmalloc(len + 1); + *fqn = '\0'; + + p = fqn; + for (i = 0; i < count; i++) + p = stpcpy(p, list[i]); + + return fqn; +} + +static void process_fqn(Dwarf_Die *die) +{ + process(" "); + process(get_fqn(die) ?: ""); +} + +#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \ + static void process_##attribute##_attr(Dwarf_Die *die) \ + { \ + Dwarf_Word value; \ + if (get_udata_attr(die, DW_AT_##attribute, &value)) \ + process_fmt(" " #attribute "(%" PRIu64 ")", value); \ + } + +DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment) +DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size) +DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding) + bool match_all(Dwarf_Die *die) { return true; @@ -93,6 +208,49 @@ int process_die_container(struct state *state, Dwarf_Die *die, return 0; } +static int process_type(struct state *state, Dwarf_Die *die); + +static void process_type_attr(struct state *state, Dwarf_Die *die) +{ + Dwarf_Die type; + + if (get_ref_die_attr(die, DW_AT_type, &type)) { + check(process_type(state, &type)); + return; + } + + /* Compilers can omit DW_AT_type -- print out 'void' to clarify */ + process("base_type void"); +} + +static void process_base_type(struct state *state, Dwarf_Die *die) +{ + process("base_type"); + process_fqn(die); + process_byte_size_attr(die); + process_encoding_attr(die); + process_alignment_attr(die); +} + +#define PROCESS_TYPE(type) \ + case DW_TAG_##type##_type: \ + process_##type##_type(state, die); \ + break; + +static int process_type(struct state *state, Dwarf_Die *die) +{ + int tag = dwarf_tag(die); + + switch (tag) { + PROCESS_TYPE(base) + default: + debug("unimplemented type: %x", tag); + break; + } + + return 0; +} + /* * Exported symbol processing */ @@ -119,6 +277,7 @@ static void process_subprogram(struct state *state, Dwarf_Die *die) static int __process_variable(struct state *state, Dwarf_Die *die) { process("variable "); + process_type_attr(state, die); return 0; } -- 2.47.0.163.g1226f6d8fa-goog